Group Meeting 2001 July 19 Thursday 11:30

I. Old Business

• Changes on computers in terms of where you access programs.  Scott aims to finish today.
  • Purpose:  will use less hard disk space, allow us to update versions of programs in only one place, automatically leaves feffit on the screen.
  • Setup:  Scott will put batch files on desktop icons like “Autobk.bat.”  Copy them into where you’re doing the fit.
  • Separate folders:  folder for each sample and one for feff.  To find appropriate feff file, add  “..\feff\” to path command….will read:
    • Path1..\feff/feffit0001.dat.
• Exafs manual
  • Sample section from John.
  • “At the run” can be added to; feedback, changing energy and gas, adjusting monochromator, water in displex, etc.  Troubleshooting section.  What to do if…no I0?  No edge jump?
  • How to connect to internet at the NSLS.
  • Mike Rivlin was to write a chemical inventory section.
  • Hershie will do a more detailed revision of the “steps for analysis” section.
  • Theanne will do formatting and editing.
  • Scott will send us his dissertation…we will include Fourier transform section and multiple scattering section to the manual.

II. August run

• Samples
  • first priority are the tin samples…anode battery materials.  Very low L edge, perhaps below the range on X23B.  Will run the K edge, but it is too high for X23B.  Can swap times with X11A (orB) which is an unfocused beam but fairly easy to run.  However, the dates change to the first week of classes, beginning Sun, August 26 and ending either the 28^th or 29^th.
  • Cycler?  Perhaps. If so, we need to contact the NSLS cycler tech.
  • Quantum dots?  No.
  • Schedule:  Theanne—Sun or Tues or both.  Mike B.—Sunday.  Mark—Monday-Tuesday.  Marten—Sun-Mon.

III. Progress Reports

• Scott
  • revising Pyrites paper.  Two locations scanned on each sample, Scott analyzing second location now using input file from the first locations.  Corrected an error in Eo.  The one interesting result, a dramatic new phase, turned out not to exist.  New phase may have been due to error in Eo.   There is some interesting disconnect between the near edge and the exafs—more metallic iron seems to be present in near edge.  Metallic iron particles may be extremely small nanoparticles and as a result do not show up in the exafs.
  • Dissertation—working away at it.  Gaining a better understanding of windowing and of how much unevenness in sample affect exafs.  May mess up the edge jump a lot but doesn’t seem to affect the exafs much.  For a sample with one half twice as thick as the other, Scott found a difference of 10%, but found no affect in the limit of a thin sample and the limit of the thick sample.  Same result for a pinhole sample.  Scott believes it may distort the normalization through problems at the edge jump.
• Hershie - having problems running feff8 on the vanadates.  Working on pyrites research paper.
• Mike B.- Fe fit—working on multiple scattering constraints.
• Mike R. – Cu fit.  Graphed correlated variables.  Lost data.
• Theanne—photovoltaics and Berkeley-Stanford synchrotron summer school.
• Mark—Finished Ni.  Working on Fe.

IV. Next Group Meeting—Thursday, August 2, 1 pm.  Mike B. will bring food.